Has a Hard Freeze Occurred Yet? (NWS Frost and Freeze Products)

As we continue through autumn, the growing season over north-central and northeastern South Dakota and west-central Minnesota will gradually be coming to an end.  Although some locations have fallen below 32F this fall (see map below courtesy of the Midwest Regional Climate Center), a hard freeze (with temperatures in the upper-20s) has not occurred over a majority of the area.

 

HIGH PRESSURE SETTLED OVER THE REGION EARLY ON THE MORNING OF SATURDAY, OCTOBER 2ND AND BROUGHT COLD TEMPERATURES TO MUCH OF THE AREA.  MUCH OF CENTRAL AND NORTHEASTERN SOUTH DAKOTA REPORTED FROST...WITH A FEW LOCATIONS RECORDING THEIR FIRST FREEZE OF THE YEAR.  BELOW IS A LIST OF SITES WITH THEIR RESPECTIVE LOW TEMPERATURES FROM SATURDAY MORNING. DATA WAS GATHERED FROM ASOS...AWOS...SDSU AND RAWS OBSERVATION SITES.

 

32 DEGREES OR LOWER (HARD FREEZE)...

TIMBER LAKE.............................27

MOBRIDGE..................................27

HERREID......................................27

ANDOVER.....................................29

HIGHMORE..................................29

BEAR CREEK RAWS...................29

BOWDLE........................................30

KENNEBEC....................................30

GANN VALLEY.............................31

PIERRE SDSU..............................31

WATERTOWN.............................31

BRITTON......................................32

GETTYSBURG..............................32

SOUTH SHORE...........................32

SAND LAKE RAWS....................32

 

33 TO 36 DEGREES (FROST CONDITION)...

MCINTOSH...................................33

PIERRE ASOS...............................33

FAULKTON....................................33

ABERDEEN.....................................33

EAGLE BUTTE...............................34

OACOMA........................................34

SISSETON.....................................34

WHEATON.....................................34

HURON RAWS..............................34

GRAND RIVER RAWS................35

MARSHALL COUNTY RAWS...35

LEOLA..............................................36

LAKE COCHRANE.........................36

ORTONVILLE................................36

$$

TMT/TMK

 

As such, the NWS in Aberdeen will continue to issue several products to alert agricultural users for the potential for frost or freeze conditions.  These products will be issued until the following:

1)   a hard freeze occurs over a majority of the area

2)  until October 15th (statistical end of the growing season) 

 

 Descriptions of the NWS Products: 

Freeze Watch:   Issued when conditions are favorable for temperatures to fall below 32 degrees Fahrenheit during the next 12 to 48 hours resulting in the possibility for significant damage to unprotected vegetation. 

Freeze Warning:  Issued when confidence is high that temperatures will fall below 32 degrees Fahrenheit within the next 24 hours resulting in significant damage to unprotected vegetation. 

Frost Advisory:  Issued when conditions are favorable for temperatures to drop between 33 and 36 degrees Fahrenheit resulting in the possibility of widespread frost near the surface.  Unprotected vegetation may be damaged.

 

Average Dates of First Frost and Freeze:

Below are graphical depictions of the median first frost/freeze dates across the upper Midwest, along with a table that provides a local summary of the date when temperatures of a given threshold are expected to be met.  The graphical images are compliments of the Midwest Regional Climate Center.

 

Median Date for 32F Freeze:

 

Median Date for 28F Freeze:

 


Tabular Listing of Frost/Freeze Dates:

For example, in Aberdeen, the average (or mean) date when temperatures are first expected to fall to 32F occurs on September 22nd.  Similarly, 90 percent of time, temperatures in Aberdeen will have fallen at or below 28F by October 15th.

 

ABERDEEN 36F 32F 28F 24F
90th 25-Sep 7-Oct 15-Oct 30-Oct
75th 21-Sep 29-Sep 9-Oct 20-Oct
50th 15-Sep 22-Sep 30-Sep 11-Oct
Mean 13-Sep 22-Sep 1-Oct 11-Oct
         
PIERRE 36F 32F 28F 24F
90th 2-Oct 18-Oct 28-Oct 7-Nov
75th 29-Sep 10-Oct 22-Oct 31-Oct
50th 21-Sep 4-Oct 12-Oct 23-Oct
Mean 22-Sep 4-Oct 13-Oct 22-Oct
         
WATERTOWN  36F 32F 28F 24F
90th 27-Sep 7-Oct 14-Oct 29-Oct
75th 21-Sep 1-Oct 10-Oct 21-Oct
50th 16-Sep 24-Sep 3-Oct 10-Oct
Mean 13-Sep 23-Sep 3-Oct 11-Oct
         
MOBRIDGE 36F 32F 28F 24F
90th 4-Oct 13-Oct 26-Oct 5-Nov
75th 27-Sep 7-Oct 16-Oct 30-Oct
50th 18-Sep 28-Sep 6-Oct 22-Oct
Mean 19-Sep 29-Sep 6-Oct 19-Oct

 



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